Detection of a weight of mobile bodies, such as automobiles and railway vehicles, that load a cargo is generally performed in a static environment using a load cell. Various techniques for detecting a weight of a mobile body itself and that of a loading cargo during traveling have been proposed, however, at present, they have not yet been established (made possible to be put into practical use and commercialized). Then, the present applicant has proposed a cargo weight prediction device that, by applying the center-of-gravity detection theory, predicts the weight of a cargo that is loaded on a trailer truck (for example, refer to Patent Document 1).